This invention relates to an enclosure for electrical cables and more particularly to an apparatus for encapsulating and sealing a cable splice.
A wide variety of cable enclosures are in use to protect electrical cables that are spliced or prepared to be spliced against hostile environments. For example, in telephone communication systems, it is frequently necessary to splice into one or more of the cables for maintenance, repair or replacement purposes. Often, the cables to be spliced into the system are prepared with terminal connectors for easy connection with mating connectors in the system. Such prepared terminations are also enclosed to protect against the environment during storage and shipment until spliced into the system. Whether for permanent or temporary purposes, it is desirable that the enclosures be properly sealed to protect exposed cable conductors against deterioration caused by moisture, gases or other contaminants, as well as to prevent electrical short circuiting.
It is common practice in this art to form a seal using a foamed plastic such as a polyurethane resin. Such polyurethane resins are readily available and relatively easy to handle. Polyethylene resins have become widely used as a insulating material in electrical cables and also in enclosure casings due to their favorable insulator properties. However, since polyethylene resins are chemically stable, they adhere poorly to the polyurethane resins, in particular under high pressure. Moreover, since the influence of the mutually different thermal expansion coefficients of polyethylene resins and polyurethane resins is enlarged by changes in the environment temperature, the integrity of the adhesion therebetween is further diminished, resulting undesirably in intermittent or completely open seals.
While other components, materials and enclosures may be utilized to provide proper sealing, the use, for example, of petroleum jelly compounds or grease is particularly disadvantageous where ready access to the spliced cable or cable termination is sought and simple, inexpensive installation is desired.